# # 顺序语句
# print(1)
# print(2)
# print(3)

# 条件语句

# a = int(input("输入1表示认真学习,输入2表示躺平: "))
# if a == 1:
#     print("你能拿到心仪的offer")
#
# if a == 1:
#     print("你能拿到心仪的offer")
# else:
#     print("你不能拿到心仪的offer")
#
# if a == 1:
#     print("你能拿到心仪的offer")
# elif a == 2:
#     print("你不能拿到心仪的offer")
# else:
#     print("输入无效")

# a = input("请输入一个整数: ")
# if a == '1':
#     print("aaa")
#     print("bbb")
# print("ccc")

# a = input("请输入一个整数: ")
# if a == '1':
#     print('aaaa')
# else:
#     print('bbbb')
# print('cccc')

# (1) 输入一个整数, 判定是否是奇数
# a = input("请输入一个整数: ")
# a = int(a)
# if a % 2 == 1:
#     print("奇数")
# else:
#     print("偶数")

# (2) 输入一个整数, 判定是正数还是负数
# a = int(input("请输入一个整数: "))
# if a > 0:
#     print("正数")
# elif a < 0:
#     print("负数")
# else:
#     print("0")

# (3) 判定年份是否是闰年
# # 1.可以被4整除的年份
# # 2.是世纪年(被100整除) ,同时可以被400 整除
# year = int(input("请输入年份: "))
# if year % 100 == 0:
#     if year % 400 == 0:
#         print("闰年")
#     else:
#         print("平年")
# else:
#     if year % 4 == 0:
#         print("闰年")
#     else:
#         print("平年")

#循环语句

#while循环
# 打印 1-10 的整数
# a = 1
# while a <= 10:
#     print(a)
#     a += 1

# 计算1 - 100的和
# theSum = 0
# a = 1
# while a <= 100:
#     theSum += a
#     a += 1
# print(theSum)

# 计算 5 的阶乘
# a = 1
# result = 1
# while a <= 5:
#     result *= a
#     a += 1
# print(result)

# 求 1! + 2! + 3! + 4! + 5!
# a = 1
# theSum = 1
# while a <= 5:
#     b = 1
#     result = 1
#     while b <= a:
#         result *= b
#         b += 1
#     a += 1
#     theSum += result
# print(theSum)

#for循环
# 打印 1-10
# for a in range(1, 11):
#     print(a)


# 打印 2, 4, 6, 8, 10
# for a in range(2, 12, 2):
#     print(a)

# 打印 10-1
# for a in range(10, 1, -1):
#     print(a)

# 求 1 - 100 的和
# theSum = 0
# for a in range(1, 101):
#     theSum += a
# print(theSum)

# continue
# for a in range(1, 6):
#     # 在第三个包子中发现了虫子
#     if a == 3:
#         continue
#     print(f"吃第{a}个包子")

# break
# for a in range(1, 6):
#     # 吃到第三个是吃到一半发现吃到了虫子
#     if a == 3:
#         print(f"吃第{a}个包子")
#         break
#     print(f"吃第{a}个包子")

# 输入若干个数字, 求平均值. 使用 "分号" 作为结尾.
theSum = 0
count = 0
while True:
    a = input("请输入数字: ")
    if a == ';':
        break
    a = float(a)
    theSum += a
    count += 1
print(theSum / count)